ASSAY FOR INITIATORS AND PROMOTERS OF CARCINOGENESIS BASED ON ATTACHMENT-INDEPENDENT SURVIVAL OF CELLS IN AGGREGATES

  • 1 January 1983
    • journal article
    • research article
    • Vol. 43  (1) , 320-323
Abstract
A cell line (HRRT) derived from a hereditary renal rat tumor was used in an assay for initiators and promoters of carcinogenesis based on attachment-independent survival in aggregates. Treatment with single noncytotoxic doses of the carcinogens urethan (1 mM), N-methyl-N-nitrosourea (30 .mu.M), and benzo(a)pyrene (0.2 .mu.M) for 1 h did not affect survival of HRRT cells in the aggregate assay system. However, when carcinogen treatment was followed by exposure of the cells to the potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (0.16 .mu.M), a considerable increase in survival was observed. With urethan as an initiator, tumor promoters (12-O-tetradecanoylphorbol-13-acetate and phorbol-12,13-didecanoate) induced a considerable response in the assay system, while nonpromoting phorbol esters (4-O-methyl-12-O-tetradecanoylphorbol-13-acetate and 4.alpha.-phorbol-12,13-didecanoate) did not affect the survival. Exposure of HRRT cells to NiSO4 (40 .mu.M) for 3 h did not influence cell survival in the aggregate form. However, subsequent treatment of the cells with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate induced a marked increase in the number of viable cells. Moreover, treatment of HRRT cells with a nontransforming dose of urethan (1 mM) for 1 h followed by continuous exposure to nickel sulfate (40 .mu.M) also increased cell survival in the aggregate form. Nickel sulfate may act as both an initiator and a promoter in mammalian cell transformation. The aggregation assay system using the HRRT cell line may be a valuhable in vitro screening assay for putative initiators and promoters of carcinogenesis.